Organic electroluminescent materials and devices

1. A compound comprising a first ligand L A of

wherein ring A is a 5- or 6-membered carbocyclic or heterocyclic ring;

wherein X is NR, O, or S;

wherein R A and R B each represents mono to a maximum possible number of substitutions, or no substitution;

wherein R A and R B are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof,

wherein R is selected from the group consisting of hydrogen, deuterium, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, and combinations thereof;

wherein any adjacent substitutions in R, R A and R B can be joined or fused into a ring;

wherein Z 1 is an anionic coordinating atom selected from the group consisting of C and N;

wherein the ligand L A is coordinated to Ir or Pt;

wherein L A is a bidentate ligand when it is coordinated to Ir;

wherein Ir or Pt can be coordinated to other ligands.

2. The compound of claim 1 , wherein R A and R B are each independently selected from the group consisting of hydrogen, deuterium, fluorine, alkyl, cycloalkyl, heteroalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, and combinations thereof.

3. The compound of claim 1 , wherein ring A is a 6-membered aromatic ring.

4. The compound of claim 1 , wherein ring A is a 5-membered aromatic ring.

5. The compound of claim 1 , wherein A is benzene.

6. The compound of claim 1 , wherein the anionic coordinating carbon is an sp2 carbon atom of a 5- or 6-membered carbocyclic or heterocyclic ring selected from the group consisting of benzene, pyridine, furan, thiophene, and pyrrole; or

wherein the anionic coordinating nitrogen is an sp2 nitrogen atom of an N-heterocyclic ring selected from the group consisting of imidazole, benzoimidazole, pyrazole, pyrrole, and triazole.

7. The compound of claim 1 , wherein R and an adjacent R B are joined together to form a 5-membered or 6-membered heterocyclic ring.

8. The compound of claim 1 , wherein the first ligand L A is selected from the group consisting of:

wherein R 1 , R 3 and R 4 are each independently selected from the group consisting of hydrogen, deuterium, fluorine, alkyl, cycloalkyl, heteroalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, and combinations thereof, and

wherein R 3 and R 4 can be joined to one another to form a ring.

9. The compound of claim 1 , wherein the first ligand L A has Formula II

wherein A 1 , A 2 , A 3 , and A are each independently C or N;

wherein at least two adjacent ones among A 1 , A 2 , A 3 , and A 4 are C and are fused to a structure of Formula III

wherein Y is NR′, O, or S;

wherein A 5 , A 6 , A 7 , and A 8 are each independently C or N;

wherein R C has the same definition as R A ; and

wherein R′ has the same definition as R.

10. The compound of claim 1 , wherein L A is selected from the group consisting of:

11. The compound of claim 1 , wherein the compound has a formula of M(L A ) x (L B ) y (L C ) z ;

wherein L B and L C are each a bidentate ligand;

wherein x is 1, 2, or 3; y is 1 or 2; z is 0, 1, or 2;

wherein M is Ir or Pt; and x+y+z is the oxidation state of M.

12. The compound of claim 11 , wherein L B and L C are each independently selected from the group consisting of:

wherein each X 1 to X 13 are independently selected from the group consisting of carbon and nitrogen;

wherein X is selected from the group consisting of BR′, NR′, PR′, O, S, Se, C═O, S═O, SO 2 , CR′R″, SiR′R″, and GeR′R″;

wherein R′ and R″ can be fused or joined to form a ring;

wherein each R a , R b , R c , and R d represents from a mono substitution to a maximum possible number of substitutions, or no substitution;

wherein R′, R″, R a , R b , R c , and R d are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, and

wherein any two adjacent substituents of R a , R b , R c , and R d can be fused or joined to form a ring or form a multidentate ligand.

13. The compound of claim 11 , wherein the compound is Compound Ax having the formula Ir(L Ai ) 3 ;

wherein x=i; i is an integer from 1 to 880; or

the compound is Compound By having the formula Ir(L Ai )(L Bk ) 2 ;

wherein y=201i+k−201; i is an integer from 1 to 880, and k is an integer from 1 to 201; and

wherein L Bk has the following structures:

14. An organic light emitting device (OLED) comprising:

an anode;

a cathode; and

an organic layer, disposed between the anode and the cathode, comprising a compound a first ligand L A of

wherein ring A is a 5- or 6-membered carbocyclic or heterocyclic ring;

wherein X is NR, O, or S;

wherein R A and R B each represents mono to a maximum possible number of substitutions, or no substitution;

wherein R A and R B are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof,

wherein R is selected from the group consisting of hydrogen, deuterium, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, and combinations thereof;

wherein any adjacent substitutions in R A and R B can be joined or fused into a ring;

wherein Z 1 is an anionic coordinating atom selected from the group consisting of C and N;

wherein the ligand L A is coordinated to Ir or Pt;

wherein L A is a bidentate ligand when it is coordinated to Ir;

wherein Ir or Pt can be coordinated to other ligands.

15. The OLED of claim 14 , wherein the organic layer is an emissive layer and the compound is an emissive dopant or a non-emissive dopant.

16. The OLED of claim 14 , wherein the organic layer further comprises a host, wherein host comprises at least one chemical group selected from the group consisting of triphenylene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, azatriphenylene, azacarbazole, aza-dibenzothiophene, aza-dibenzofuran, and aza-dibenzoselenophene.

17. The OLED of claim 14 , wherein the organic layer further comprises a host, wherein the host is selected from the group consisting of:

and combinations thereof.

18. A consumer product comprising an organic light-emitting device (OLED) comprising:

an anode;

a cathode; and

an organic layer, disposed between the anode and the cathode, comprising a compound comprising a first ligand L A of

wherein ring A is a 5- or 6-membered carbocyclic or heterocyclic ring;

wherein X is NR, O, or S;

wherein R A and R B each represents mono to a maximum possible number of substitutions, or no substitution;

wherein R A and R B are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof,

wherein R is selected from the group consisting of hydrogen, deuterium, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, and combinations thereof;

wherein any adjacent substitutions in R, R A , and R B can be joined or fused into a ring;

wherein Z 1 is an anionic coordinating atom selected from the group consisting of C and N;

wherein the ligand L A is coordinated to Ir or Pt;

wherein L A is a bidentate ligand when it is coordinated to Ir;

wherein Ir or Pt can be coordinated to other ligands.

19. The consumer product of claim 18 , wherein the consumer product is one of a flat panel display, a curved display, a computer monitor, a medical monitors television, a billboard, a light for interior or exterior illumination and/or signaling, a heads-up display, a fully or partially transparent display, a flexible display, a rollable display, a foldable display, a stretchable display, a laser printer, a telephone, a cell phone, a tablet, a phablet, a personal digital assistant (PDA), a wearable device, a laptop computer, a digital camera, a camcorder, a viewfinder, a micro-display, a 3-D display, a virtual reality or augmented reality display, a vehicle, a large area wall, a theater or stadium screen, a light therapy device, and a sign.

20. A formulation comprising the compound of claim 1 .